A way by which people develop awareness, concern and knowledge of the environment and its diverse values and processes...

Wednesday, September 2, 2009

INTRODUCTION TO OZONE DEPLETION

Ozoneis both beneficial and harmful to us. Near the ground, ozone forming as a result of chemical reactions involving traffic pollution and sunlight may cause a number of respiratory problems, particularly for young children. However, high up in the atmosphere in a region known as the stratosphere, ozone filters out incoming radiation from the Sun in the cell-damagingultraviolet (UV) part of the spectrum. Without thisozone layer, life on earth would not have evolved in the way it has.

Concentrations of ozone in the stratosphere fluctuate naturally in response to variations in weather conditions and amounts of energy being released from the Sun, and to major volcanic eruptions. Nevertheless, during the 1970s it was realised that man-made emissions of CFCs and other chemicals used in refrigeration, aerosols and cleansing agents may cause a significant destruction of ozone in the stratosphere, thereby letting through more of the harmful ultraviolet radiation. Then in 1985 evidence of a large "ozone hole" was discovered above the continent of Antarctica during the springtime. This has reappeared annually, generally growing larger and deeper each year. More recently, fears have emerged about significant ozone depletion over the Arctic, closer to the more populous regions of the Northern Hemisphere.In response to this and additional fears about more widespread global ozone depletion, the Montreal Protocol on Substances that Deplete the Ozone Layer was implemented in 1987. This legally binding international treaty called for participating developed nations to reduce the use of CFCs and other ozone depleting substances. In 1990 and again in 1992, subsequent Amendments to the Protocol brought forward the phase out date for CFCs for developed countries to 1995.Protecting the ozone layer is essential. Ultraviolet radiation from the Sun can cause a variety of health problems in humans, including skin cancers, eye cataracts and a reduction in the body's immunity to disease. Furthermore, ultraviolet radiation can be damaging to microscopic life in the surface oceans which forms the basis of the world’s marine food chain, certain varieties of crops including rice and soya, and polymers used in paints and clothing. A loss of ozone in the stratosphere may even affect the global climate.International agreements and other legislation have gone a long way to safeguarding this life-supporting shield. Nevertheless, for there to be real and long-lasting success, everyone must become part of the solution. Individual efforts taken together can be powerful forces for environmental change. There are a number of things that we, as individuals, can do to both protect the ozone layer. These include proper disposal of old refrigerators, the use of halon-free fire extinguishers and the recycling of foam and other non-disposable packaging. Finally, we should all be aware that whilst emissions of ozone depleters are now being controlled, the ozone layer is not likely to fully repair itself for several decades. Consequently, we should take precautions when exposing ourselves to the Sun.Causes of Ozone DepletionOzone depletion occurs when the natural balance between the production and destruction of stratospheric ozone is tipped in favour of destruction. Although natural phenomena can cause temporary ozone loss, chlorine and bromine released from man-made compounds such as CFCs are now accepted as the main cause of this depletion.It was first suggested by Drs. M. Molina and S. Rowland in 1974 that a man-made group of compounds known as the chlorofluorocarbons (CFCs) were likely to be the main source of ozone depletion. However, this idea was not taken seriously until the discovery of the ozone hole over Antarctica in 1985 by the British Antarctic Survey.Chlorofluorocarbons are not "washed" back to Earth by rain or destroyed in reactions with other chemicals. They simply do not break down in the lower atmosphere and they can remain in the atmosphere from 20 to 120 years or more. As a consequence of their relative stability, CFCs are instead transported into the stratosphere where they are eventually broken down by ultraviolet (UV) rays from the Sun, releasing free chlorine. The chlorine becomes actively involved in the process of destruction of ozone. The net result is that two molecules of ozone are replaced by three of molecular oxygen, leaving the chlorine free to repeat the process:Cl + O3 ® ClO + O2

ClO + O ® Cl + O2Ozone is converted to oxygen, leaving the chlorine atom free to repeat the process up to 100,000 times, resulting in a reduced level of ozone. Bromine compounds, or halons, can also destroy stratospheric ozone. Compounds containing chlorine and bromine from man-made compounds are known as industrial halocarbons.Emissions of CFCs have accounted for roughly 80% of total stratospheric ozone depletion. Thankfully, the developed world has phased out the use of CFCs in response to international agreements to protect the ozone layer. However, because CFCs remain in the atmosphere so long, the ozone layer will not fully repair itself until at least the middle of the 21st century. Naturally occurring chlorine has the same effect on the ozone layer, but has a shorter life span in the atmosphere.

FREON FACTS:

You may have heard much talk about Freon and new refrigerants recently. But besides knowing that it is the substance used to produce cold in your refrigerator, many of its characteristics usually remain a mystery to most.

Some of the more common misconceptions are, that eventually, more Freon needs to be added to the refrigerator, odors in the refrigerator are caused by a leak of this gas, and if it does leak inside the cabinet the food stored there is now contaminated. Surprizingly, none of these are true.

Will my refrigerator ever need to be topped up?

No, unlike automobile air conditioners, refrigerators should never need to be topped up. They never need any more refrigerant than they came with from the factory, unless they develop a hole. Holes can be a result of mechanical damage, or from a defect that shows up later in the refrigerator's life because of unanticipated design faults in the refrigerator. Small holes can exist right from when the refrigerator was new and take from one to six years to show their symptoms. In the past, these refrigerators were merely topped up by technicians. The refrigerator could work normally, while leaking out refrigerant gradually. Nowadays however, topping up is no longer an acceptable practice. The hole must be found and repaired, or the refrigerant must be immediately removed before any more Freon escapes.

I seem to always have a gassy smell in my refrigerator. Does this mean it has a small leak?

No, the only time odor is caused by the substances in the hermetic system, is during a large hole situation. In this case, all the refrigerant leaks out and air enters the system. If the compressor is then allowed to stay running, a few hours or perhaps overnight, a pungent oily odor will occur.

What happens is that the electric motor of the compressor is not designed to cut itself out at temperatures above which it will burn the varnish off its windings in an oxygen atmosphere. The mineral based oil that is present in the hermetic system with the refrigerant also darkens and develops an odor when subjected to high heat and oxygen.

So by the time a hermetic system gives off this kind of odor, your refrigerator would no longer be functioning, not even a little bit. The gassy smell you are noticing is coming from a different source.

In my existing refrigerator, can I have the Freon removed and replaced with new ozone friendly refrigerants?

Yes, currently there are many drop-in replacements that can be substituted in either R12 systems or 134a systems. The most common ones presently used are SP34e and R414. There are also two blended refrigerants R406 and R409 that can be used as direct replacements. The new refrigerants will work in your present refrigerator but can't be mixed with other refrigerants. At this time many technicians are using cross compatible refrigerants such as SP34e and R414 but if enough can be recovered and if your system is still clean and none has escaped or been contaminated by air or moisture, the original R12 or 134a can be put back in if the technician has a bit more to make up the difference in what could be recovered. (no recovery can be 100%). If the company has the right equipment they can remove your existing refrigerant, filter it, then return it into your system after a repair, such as a compressor replacement, is complete. At this time new R12 is no longer available and all new refrigerators use 134a.

134a can't be used in an R12 system . This is because the oil used with 134a is incompatible with the oil used in R12 systems. One of the properties of the oil in a vapor compression system is that it atomizes within the refrigerant and circulates with it. Because of the new cross compatible refrigerants, retrofitting an existing system no matter which refrigerant it used is quite a simple matter.

Is Freon or any of the new replacement gasses flammable or explosive?

Freon or 134a is not, but R406, in certain very remote circumstances, could be. R406 is a blended gas that is made from three separate substances HCFC-22=55%, HCFC-142b=41%, and Isobutane=4%. The small portion of Isobutane can cause this replacement to be weakly flammable during leakage. Because of this and the fact also that HCFC-142b has one of the highest ODP's of the HCFCs, a different blend, R409 is becoming more favorable. It is made of the three substances HCFC-22=60% , HCFC-124=25% , and HCFC- 142b=15% . Notice HCFC-142b is a component of R409 but only 15% and it uses no Isobutane.

Is Freon or any of the new replacement gasses toxic?

No, in fact until recently Freon was, and still is in some instances, used to propel medicine directly into the lungs of asthma sufferers. In 1931 the inventor of Freon, Thomas Midgley made a public demonstration that it was harmless by filling his lungs with the gas then blowing out a candle.

If Freon is so non toxic, why is it being banned?

The current scientific theory states that it is because of Freon's eventual effect on the ozone, high up in the earth's atmosphere. The family of Freon type gasses work their way higher and higher into the atmosphere due to kinetic reaction with the other molecules in the air. When released to the atmosphere Freon gradually rises up, even higher then the ozone layer. Once it is higher than the ozone layer it is no longer protected from ultra violet light. Ultraviolet light acts on Freon by breaking it down to its original components. One of these components is chlorine. The liberated chlorine then starts falling back down through the ozone layer changing ozone molecules back to oxygen. Worse yet, what happens on this molecular level is that just one chlorine molecule can destroy millions of ozone molecules on it's way through.

Why is ozone necessary in our atmosphere?

Ozone, in chemical notation as O3, is merely oxygen with three molecules instead of two. It acts like a filter and prevents harmful infrared and ultraviolet rays from entering the lower atmosphere. This is the spectrum of light that is harmful to life on earth. What happens actually is this light causes DNA. strands, present in all living cells, to tangle. In larger organisms, such as a human being, the effect can cause cancer. The organisms most vulnerable to these harmful rays would be the photo plankton that grow on the surface of our oceans. If they were to be destroyed, the entire food chain would be disrupted. This would catastrophically affect all life as we know it. The entire ecosystem could die, and of course we would go with it.

So releasing Freon into our atmosphere has very serious consequences, so serious that the scientists have set limits on virgin production of tapering off to zero. There are also laws being established to make it a criminal offense for anyone who releases, or causes to be released, any ozone depleting substance including Freon. This is why you should never tamper with your hermetic system. Only professional technicians have the appropriate qualifications and equipment to do this work.

Does this mean I'll eventually have to get rid of my refrigerator because it uses Freon?

At this point the chances of that happening are highly unlikely. Refrigerators use very little Freon usually between 4 and 8 ounces. The chance of them starting to leak during normal operating conditions is quite slight. And unlike an automobile's air conditioner, they never need to be recharged and, for that matter, very seldom get into collisions. :>)

The meaning of the term hermetic means the system is sealed to the atmosphere. On a typical refrigerator compressor , its electric motor runs right in the Freon gas, the only connection to the outside is the three electrical terminals. Another factor in your refrigerator's favor is that there are just so many of them. The new blended drop in replacements for R12, R406 and R409 will currently be available until the year 2020.

How should I get rid of an unwanted refrigerator or freezer?

If you are planning to discard any refrigerating appliance that contains Freon, you should have a qualified technician remove and recycle the Freon. Check on this first though, some landfill sites in larger cities are now providing this service.

There may be an easier way though. If you live in a larger center, chances are there are companies that will come to your home free of charge, or pay you a nominal sum to take your used appliance for parts or resale. Failing this, you could haul it into a larger center and drop it off at an appliance recycling or repair shop on your next shopping trip. Be sure to phone ahead and make arrangements with them first.

Is it environmentally prudent to repair my Freon type refrigerator?

Yes, in fact continuing to use it at this time instead of discarding it and buying a new one, is still kinder to the environment, however this is only my opinion. Of course stores selling new refrigerators may have a different one.

Manufacturers are now finally having to comply with new regulations regarding energy consumption. This could have been done a long time ago but there was no motive. Because of this redesigning though, many "bugs" are present that have to be worked out and sometimes the consumer ends up paying for them. On the large scale across the entire nation, the difference in energy consumption is significant, but on an individual basis it likely won't make that much difference to your power bill if you have a 70's or a 90's design.

What would be nice to see, is regulations on new appliances regarding durability and longevity.

Ozone Hole

In some of the popular news media, as well as in many books, the term "ozone hole" has and often still is used far too loosely. Frequently, the term is employed to describe any episode of ozone depletion, no matter how minor. Unfortunately, this sloppy language trivialises the problem and blurs the important scientific distinction between the massive ozone losses in polar regions and the much smaller, but nonetheless significant, ozone losses in other parts of the world.

Technically, the term "ozone hole" should be applied to regions where stratospheric ozone depletion is so severe that levels fall below 200 Dobson Units (D.U.), the traditional measure of stratospheric ozone. Normal ozone concentration is about 300 to 350 D.U. Such ozone loss now occurs every springtime above Antarctica, and to a lesser extent the Arctic, where special meteorological conditions and very low air temperatures accelerate and enhance the destruction of ozone loss by man-made ozone depleting chemicals (ODCs).